1. Field of the Invention
This invention relates to metal extrusion presses, and more particularly to a method and apparatus for ejecting jammed billets from indirect metal extrusion presses.
2. Description of the Prior Art
As is well known in the art, indirect extrusion presses which hold a container and a billet stationary relative to each other during the extruding operation have a number of inherent advantages over the direct extrusion presses, including: higher quality of the final product due to improved billet flow; no friction between a billet and a container; no heat generation by billets; higher extrusion speed; smaller power requirement for the press.
Therefore, indirect extrusion presses permit use of billets of longer dimensions. However, longer billets sometimes tend to stick in the container and become difficult to extrude due to temperature decrease of the hot billets or for other reasons, necessitating the removal of jammed billet from the container at the press center.
In one of the conventional mechanisms which have thus far been resorted to for removing jammed billets from the container, only short billets are used on the press so that they can be easily pushed out of the containers by ordinary operating power of the press in the event they jam in the container. This method, however, sacrifices one of the above-mentioned inherent advantages of the indirect extrusion press and is inefficient as compared with the operations with longer billets.
In another conventional method, the container is provided with a heater for raising the temperature of a jammed billet by rapid heating, thereby facilitating the removal of the billet. This method, however, has the drawback that large equipment costs are incurred, coupled with the complication of the construction and inconveniences in handling.
In an even worse case, a container containing repairs of a jammed billet has to be dismantled from the press machine to be scraped off manually, in spite of the heavy and time-consuming job of dismantling and reassembling the container.